Officials conducted raids soon after the deadline expired

The authorities say at least 500 people were arrested on Tuesday, when an amnesty for illegal workers to leave the country expired.

Those arrested could face heavy fines, jail sentences and whipping.

Several hundred thousand people left before the deadline, but at least 200,000 have chosen to stay.

In total, the papers of more than 5,000 migrant workers were checked on Tuesday, according to Malaysian Home Minister Azmi Khalid.

More than 550 people were then taken into custody after being found to be in the country illegally, officials said.

'Better than Guantanamo'

Mr Azmi said Malaysia would persist with the crackdown, despite complaints by human rights groups over the treatment of foreign immigrants.

"Compared to Guantanamo Bay, we are a five-star hotel," he told the Associated Press.

"We do not do things that are inhumane. This is our guarantee."

The deadline for illegal workers to leave Malaysia has been extended three times since the policy was first announced in October, but the crackdown finally seems to have begun in earnest.

Police officers, immigration officials and more than 300,000 volunteer reservists launched their round-up operation shortly after the deadline passed at midnight on Tuesday.

ILLEGAL WORKFORCE 400,000-600,000 foreigners have already left At least 200,000 remain Many work in construction, plantations and domestic service They risk jail, fines and whipping if found

The squads visited building sites, plantations and restaurants - all popular work places for illegal migrants.

One of their first stops was a construction site outside the capital where, according to reports, at least 40 foreigners were arrested having failed to produce proper documentation.

Deputy Prime Minister Najib Razak said illegal immigrants who remained in Malaysia would be given no more chances.

"We do not need to hear pleas, it doesn't matter anymore. They chose to remain defiant, they have to face the music," official news agency Bernama quoted him as saying.

The illegal migrants, most of whom are from Indonesia, with others from Burma, India, the Philippines and Bangladesh, argue that job opportunities are scarce at home, or that they are still owed wages by their Malaysian employers.